There are various structures of electric junction boxes installed in an automobile in accordance with car type, e.g., an electric junction box 201 as shown in FIG. 6 that includes a plurality of cassette blocks 202, 202 on which electric component 211 is mounted, a main body case accommodating these cassette blocks 202, 203, and a upper cover 207 (refer to the PTL 1).
The aforementioned cassette blocks 202 and 203 are provided with a lock structure (not shown) locking into each other, and brackets 221, 231 adapted to be fixed to a bottom wall 260 of the main case 206 with a bolt 204 and a nut 205. These cassette blocks 202, 203, while assembled to each other by the lock structure, are inserted into the main case 206. The bolt 204 preliminarily assembled to the main body 206 is passed through a through hole disposed in the brackets 221, 232, and the nut 205 is threaded into the bolt 204, and thereby the cassette block 202, 203 are fixed to the main case 206.